1. Field of the Invention.
The present invention relates generally to improving the aerodynamic conditions on objects moving through fluid mediums and more particularly to a method and system for (1) reducing aerodynamic drag on athletes, (2) increasing aerodynamic lift and stability on athletes and/or (3) increasing the athlete's ability to transfer heat away from the body. The effect is attained by providing trip mechanisms at preselected locations along the athlete's body to prematurely trip the boundary layer of fluid medium around the body from laminar to turbulent flow thereby establishing a boundary that has more momentum and when properly applied achieves the aforementioned results.
2. Description of the Prior Art.
Athletic events where speed is the common denominator among winners is becoming more and more an event involving, not only a good and gifted athlete, but also ingenuity and high technology. This is evident by the equipment, i.e., clothing, shoes, wax, shapes, geometries, materials, designs, etc., currently being used by athletes as compared to an athlete of the 1950's. In today's sporting events the difference in first and second place is measured in milliseconds. This supports the fact that the best equipped athlete and the athlete that experiences less aerodynamic drag, increased aerodynamic lift, or increased heat dissipation capability will stand a better chance of winning an event.
There are two basic components of aerodynamic drag, namely (1) skin friction drag and (2) pressure drag. Fluid flow can be categorized as viscous or inviscous, laminar or turbulent, and compressible or incompressible. The fluid flow about an athlete is considered viscous and incompressible and depending on the speed of the sport and the geometry of the body part, the flow is laminar or turbulent. For a body in a viscous flow, a boundary layer exists near the body. Only in the boundary layer are the effects of the fluid viscosity important. In this boundary layer there is a velocity profile (relative to the body) of the fluid ranging from zero at the surface of the body to a free stream velocity at a finite distance from the body. The finite distance from the body to the point where the fluid velocity equals the free stream velocity is termed the boundary layer thickness and is a function of velocity and geometry. The velocity gradient in this boundary layer results in a shear stress acting between differential layers of fluid. This is the origin of the skin friction drag component. The boundary layer in turbulent flow is thicker than that for a laminar flow and as a result the turbulent boundary flow possesses more momentum than a laminar boundary flow. Reducing the skin friction on a body tends to reduce the thickness of the boundary layer, i.e. minimizes the viscous forces acting on the body.
The pressure drag component is possibly best illustrated by reference to the fact that a circular cross-section will experience a much higher drag force than a well-streamlined body that has the same projected area into the flow stream. This is because the circular body leaves behind a large wake whereas the streamlined body has only a small wake if any. The larger the wake the larger the drag force. The fluid pressure in the wake of the body is lower than the fluid pressure acting on the front of the body thus a force resulting from the pressure differential resists the motion of the body. This force is termed pressure drag. The dominating drag component on a bluff body is, in the velocity ranges in which most athletes compete, the pressure drag component.
By overcoming the skin friction drag and pressure drag on the body of an athlete, the athlete's performance can be enhanced where speed is important to performance. Similarly, in events such as ski jumping, increased speed in addition to the lift and stability experienced by an athlete has a direct bearing on how far the athlete can fly before gravity returns the athlete to ground level. It is also well known that increasing an athlete's heat dissipation capability during performance, within bounds, enhances the athlete's performance.
The present invention has been made to achieve advantageous effects on an athlete caused by the afore-noted normally occurring aerodynamic characteristics as the athlete moves through a fluid medium.